Braking mechanism



` AJuly 13, 1926. 1,592,185

.'r. A, DOHERTY 'Er AL BRAKING MECHANISM Filed hun@ 23, 1923 Patented July 13, 1926;-

THOMAS A. DO'HERTY `AND. RAYMOND e..WooDRUFF, oF

, sYI/VANIA.

PHILADELPHIA, PENN- BRAK'ING MECHANISM.

Application mea 'June 2s, 192s. serial No. 647,218.

Our, invention is designedto provideimproved braking mechanism having a .plurality of brake shoes each radially movable-l against the annular face of a brake drum by a cam block having integral shoulders engaging the. shoes, so as to apply uniform pressure throughout ,substantially the entire-surfaces of the braking members Without the noise, wear,l and breakage, incident to the use of previous devices.

. ln its preferred form, 4our invention come prises a plurality of radially movable brake shoes having arcuatefbearing faces symmetrically arrangedsoasto form a substantially complete circle conforming with 'the bearing surface of a brake drum, the shoes having .inner bearing surfaces' so disposed as to lie l in the path of rotation of the integral cam, shoulders of a journalledblock having v Within the periphery. thereof a toothed collar engaged by a journalled gear, the operation of which rotates the block to expand the shoes against the drum. `The shoesA4 are'normally retracted and held out `of engagement with the drum by springs 'connecting the several shoes and acting to draw them toward a common center, 'and the inner faces ofthe shoes when so contracted preferably forming an 'outline similar to the outline of the expanding block which lies between them. f

The characteristic features `of, -our improvements will more fully appear from lthe following 'description and 'the accomferred embodiment lofour invention.

'In the drawings, Fig. 1 1s a vertical sectional view of apparatus embodying our invention taken on the line 1-1 of Fig; 3;

talen 'on the line 2-2 lof Fig.`3; Fig. 3

is a vertical transverse sectional view Vof thev on which are fixed radial beveled tenons 3 and a hollow hub 4 through vwhich a spindle 5 passes to drive the wheel 6; an annular brake drum 7 registering with the plate 2, being fixed to the wheel 6.

A block 8 is journalled on the hub 4 and is provided with a toothed collar 9 within "10 of the block with the-tenons 3. A shaft panyihg drawingsin illustration of a pre-A Fiv. 2 is a vertical sectionalrview thereof the 'periphery of the block and bearing against the plate 2, thereby'spacing the body of theblock from the plate and preventing engagement of the integral cam shoulders 11,' journalled inthe plate 2, has fixedthereon a lsegmental gear 12,` engaging the 'toothed collar 9; a lever 13 being fixed on drum 7 and plate'2, each shoe comprising fan arcuate bearing member or flange 14, a

chord bearing member or flange 15 connect- 7o ing the ends of the flange 14, anda web 16 connecting and transmitting thrustbetween the flanges. The flanges 14 and 15 contain undercut ways 17 for engagement with the beveled tenons 8, so that-the shoes are movable only radially with respect to the annular surface of the drum 7.

Each shoe is connected with two other1 shoes by coiled springs 18 which tend to draw the shoes toward a center and .away from-the brake drum.

It Will be understood that the block 8 is normally so positioned that its sides .lie sub stantially parallel with and within the similar contour formed by the shoe flanges 15, the shoes being drawn inward by the springs 18.` l/Vlienthe lever 13 is rocked, in any suitable manner, the segmental gear 12 -theintegral cam shoulders 10 into engagement with the faces of the bearings 15 `of the shoes, which are thereby thrust outward radially against the inner bearing surface of thedrum 7, and uniform braking is'elfected throughout the entire peripheries of the braking inembers Should it he desirable for any reason to Aadjust the relationship of the Ablock 8 with vthe shoes or with the gear 12, suchblock may be readily withdrawn from its hub and turned sufficiently to effect- 100. thev 'desired adjustment, then restored to its hub with the gear`12 in engagement with appropriate teeth of' thecollar 9. y l-laving described our invention, we claim:

1. Braking mechanisms-comprising a face plate, a -drum rotatable relatively to-said plate, a' plurality of-,brakeshoes connected with said plate and radially movablethere; on into and out of engagement with said drum, a hub, a block mounted on said hub 11o and having integral cam' shoulders and teeth within'the eri hery thereof, a shaft journalled in szlig plate and having teeth thereon engaging teeth of said block to rock said shoulders into and out of engagement with Said shoes.

Q. Braking mechanism comprisingr a plate. adrinn`r brake shoes radially movable over said plate into engagement with said drum, and a jou'rnalled block having cams engaging' said shoes, said block having a toothed collar Within the periphery of said canisand adjacent to said plate, and a gear engaging said toothed Collaixfor rockingY said cams. i

In testimony whereof We have hereunto set our naines this 15th day of May, 1923.

THOMAS A. DOHERTY RAYMOND C. WOODRUFF. 

